Multi-band operation was discussed and introduced to 802.11ad. For example, with multi-band operation, a communication session may be transferred from the 60 Gigahertz (GHz) frequency band to a lower frequency band, such as 5 GHz. A multi-band capable device may manage operation over more than one frequency band. It may support operation on multiple frequency bands simultaneously or it may support operation on one frequency band at a time, and may then transfer to another frequency band.
Institute of Electrical and Electronics Engineers (IEEE) 802.11 supports operation on different frequency channels with different channel bandwidths and supports different transmission data rates. This results in different transmission characteristics for the different 802.11 specifications. For example, 802.11ad or 802.11aj supports very high data rates (up to 6 Gigabytes per second (Gbps)) and operates on the 60 GHz frequency band. Due to the propagation loss characteristics of this frequency band, the typical coverage range may be short, such as approximately 10 meters. 802.11n/ac operates on the 2.4 GHz/5 GHz frequency bands, which support high data rates, and where the coverage may be better than that of 802.11ad. Sub-1 GHz transmission, such as in 802.11ah or 802.11af, may provide good coverage range, while the data rate may be limited. 802.11aj is a new task group working on very high throughput to support one or more of the 40-50 GHz and 59-64 GHz frequency bands. All of these wireless frequency bands provide different but complementary characteristics in terms of coverage range and throughput. This makes multi-band operation an attractive feature. However, the existing schemes supporting multi-band operations provide only basic functionality, and advancements to these schemes are needed to address future wireless local area network (WLAN) requirements for dense networks and robust high data rates.